Switched-mode power supplies produce a highly pulsed load on the line network, which leads to harmonic currents in the line network. This load occurs in particular in the region of the voltage maxima of the sinusoidal network voltage, in which area an energy storage capacitor in the switched-mode power supply is recharged. The harmonic load on the line network can be indicated by a so-called power factor value, whose value is less than or equal to unity and may, for example, be determined by means of appropriate measurement signals. Regulations for a lower power factor limit have already been introduced in various countries.
A switched-mode power supply which produces a reduced harmonic load on the line network is known, by way of example, from EP-A-0 700 145. Apart from a first current path, via which an energy storage capacitor in the switched-mode power supply is charged, this contains a second current path which has an inductance and produces a connection between a filter capacitor downstream from the network-?? rectifier, and a tap on the primary winding of the transformer. The inductance in this case acts as an energy store, which is charged in the phase when the switching transistor is switched on, and which then emits this energy to the energy storage capacitor in the phase when the switching transistor is switched off.
A further development of this switch-mode power supply is disclosed by a power factor correction circuit U.S. Pat. No. 5,986,898. This contains a capacitor in the second current path, which capacitor limits the current and in this way ensures the core of the inductance of the current path as well as the core on the primary winding or on the transformer do not saturate. In addition to the power factor inductance, which has a ferrite core, this power factor correction circuit also contains, in particular, the series inductance with an iron core, which acts as a damping element, in order to suppress the current pulses produced in the power factor inductance in the direction of the network connection.
EP-A-0 171 690 discloses a line deflection circuit for a television, in which a number of coil arrangements are used. A so-called bridge coil and an east-west drive coil for the deflection circuit are in this case combined in one coil arrangement, with a number of windings being arranged symmetrically alongside one another on a magnetic pin core. One of the coils, the bridge coil, is in this case subdivided into two outer windings, and the central winding corresponds to the east-west drive coil. The two windings of the bridge coil are in this case arranged with magnetically opposing plurality, and the central winding operates in a different frequency band. The two coils in the deflection circuit are connected in parallel, and are used for two different electrical functions.